Messaging transport servers typically receive, store, and forward messages to the next server(s). In such cases, multiple high availability approaches can be deployed to ensure that such messages always exist on at least two transport servers in order to be resilient against hardware and/or software failures. However, there is a class of messages, referred to as side-effect messages, which can be generated by the messaging server, and which no other messaging servers are aware. Accordingly, such messages at each messaging server are vulnerable to loss in case of server failure. Examples of side effect messages include non-delivery reports (NDRs), delivery status notifications (DSNs), transfer agent generated messages (where a transfer agent is a mechanism that extends the basic functionality of a transport server, which may include arbitrary behavior such as generating side effect messages), journaling reports, etc. Transport components such as journaling and DSN generation can account for some of the side-effect messages based on the handling and processing of other normal or primary messages.
At the point of time when a side-effect message is generated, the side-effect message is present only on the transport server that created the message. This violates a principle in datacenters that all messages have redundant copies. If the transport server is wiped out journal-reports or DSNs may be lost. Traditional mechanisms employed to mitigate or reduce the chance of losing messages include hardware redundancies using redundantly arrayed drives, which cause an increase in the cost of goods. Meanwhile, in the cases of failures, the administrator has to worry about the state of the transport server, and hence, higher costs of administration are incurred.